Ultrasonic film splicing method

ABSTRACT

A method and apparatus for splicing two lengths of film by placing over the ends of said lengths a tape having a coating comprising a thermoplastic resin, and applying ultrasonic energy simultaneously to the overlapping portions. The apparatus includes trimming knives, and a gap to receive the knives where they will be out of the way of the ultrasonic horn.

United States Patent Gardner et al.

[451 May 9,1972

[54] ULTRASONIC FILM SPLICING METHOD [72] Inventors: Ray E. Gardner; William W. Voelckers,

both of Rochester; George T. Negus, Penfield, all of NY.

[73] Assignee: Eastman Kodak Company, Rochester,

[22] Filed: Dec. 23, 1968 [21] Appl.No.: 785,913

3,331,719 7/1967 Soloff ..156/304 OTHER PUBLICATIONS F. P. Alles, Ultrasonic Splicing of Polyethylene Terephthalate Films, Dec., 1961, The Journal of the Society of Motion Picture and Television Engineers R. S. I-Iaines, Thermoplastic Web Ultrasonic Welding Apparatus, IBM Technical Disclosure Bulletin, Vol. 8. No 5. Oct. 1965 Primary E.\aminerBenjamin A. Borchelt Assistant E.\'aminer.lames V. Doramus ArturneyWalter O. Hodsdon, Paul R. Holmes and Henry M. Chapin ABSTRACT A method and apparatus for splicing two lengths of film by placing over the ends of said lengths a tape having a coating comprising a thermoplastic resin, and applying ultrasonic energy simultaneously to the overlapping portions. The apparatus includes trimming knives, and a gap to receive the knives where they will be out of the way of the ultrasonic horn.

1 Claim, 7 Drawing Figures A/VTYHALATIO/V LAYER F/LM BASE EMULSION Patented May 9, 1972 3,661,667

Ii] m RA) 6'. GARDNER WILL/AM W. VOELCKERS GEORGE I NEGUS INVENTORS ULTRASONIC FILM SPLICING METHOD BACKGROUND OF THE INVENTION 1. Field Of The Invention The present invention relates to a novel method of an apparatus for ultrasonically splicing together two lengths or strips of thermoplastic film or web, such as moving picture film, other photographic films, or magnetic recording tape.

When handling film in such operations as processing, printing, and projection it is frequently necessary to splice two lengths together. Particularly, when developing photographic film it is customary to join or splice together a series of separate rolls of exposed film which are then passed as a continuous belt into and out of a series of aqueous processing solutions. It is imperative that the splice be strong, as a failure of a single splice during the processing operation may mean the loss of several rolls of film before the failure has been detected and rectified. The problem is particularly acute with very narrow motion picture films, such as 8mm film, because the area available for splicing is so much smaller than with the wider films.

Also, a leader of thermoplastic film (usually uncoated) must be spliced to the first length of the film to be processed to lead it into the processing solutions. A similar leader often is spliced to a length of processed film to lead it into the projector.

2. The Prior Art It has been customary in the past to join successive rolls of film together by applying to the trailing and leading ends mechanical fasteners such as staples or rivets; or an adhesive patch of material such as kraft paper having a coating of thermoplastic material which is activated by applying a heated anvil to the patch. The former tend to weaken and damage the film as the result of punching holes in the film, as well as scratching film. The latter have not been as strong as desired because the heat-activated adhesive only adheres to the coat ing on the film base, and thus is no stronger than the tenacity with which the coating itself adheres to the film base. The film base carries a rem jet antihalation layer on one side customarily, but this layer is tailored so as to adhere relatively weakly to the film base, and is purposely removed by dissolving in the alkaline processing solutions. Consequently, it has been impossible to heat splice a patch to the rem jet layer and expect to maintain the splice during processing.

Moreover, with heat splicing a dwell time is needed to permit the plastic to set, and it is frequently necessary to apply a stream of cooling air to expedite setting.

The silver halide gelatin emulsion on the other side of the film base generally adheres to the film base much more strongly, and permits a generally satisfactory splice by heat splicing. However, it would be particularly desirable for the patch to adhere directly to the film base so that there would be no problem related to the degree of adherence of the coating to the base. This is particularly troublesome for films carrying the recently introduced softer emulsions, which have relatively low internal strength and may tend to pull apart.

SUMMARY OF THE INVENTION In accordance with the present invention, we have improved upon the film splicing methods of the prior art by ultrasonically splicing a patch to the two lengths of film to be joined, in such a way that the patch is actually united to the film base to provide the strongest possible bond which will withstand the passing of the films through the various processing solutions, including the flexing of the films as they pass over various rollers.

Basically, our novel method for connecting together two lengths of thermoplastic film comprises positioning the lengths in longitudinal alignment with one another so that the trailing end of one length is adjacent the leading end of the other length. A short piece of splicing tape is then positioned in overlapping relation on narrow transverse areas of the film lengths adjacent their ends, and bridging the space therebetween. The splicing tape has at least a surface portion comprising a thermoplastic resin, and it is this portion which is in contact with the surface of the film. Then we apply ultrasonic energy from a transducer through a horn which is in contact with the overlapping portions of the tape and the film lengths, thereby uniting the tape to the film lengths.

We have found that his method is particularly advantageous when the splicing tape is applied on the rem jet side of the film, as the ultrasonic energy then seems to develop sufficient local heat at the interfaces so as to melt and stir together the rem jet layer, and the adjoining surface areas of film base and splicing tape, causing the melted rem jet to disperse in the melted thermoplastic layers. This has not been found to occur in prior art procedures, wherein the rem jet interferes with the bond.

THE DRAWING The invention will be described more in detail with reference to the drawings wherein:

FIG. 1 is a vertical sectional view, parts being in elevation, of an ultrasonic splicing apparatus in accordance with the invention;

FIG. 2 is a cross sectional view taken along the line 22 in FIG. 1;

FIG. 3 is a cross sectional view on an enlarged scale through one type of splicing tape usable in our novel method;

FIG. 4 is a cross sectional view on an enlarged scale of still another form of splicing tape;

FIG. 5 is a vertical sectional view on an enlarged scale showing the end portions of two lengths of moving picture film which have been spliced in accordance with the invention;

FIG. 6 is a vertical sectional view, parts being in elevation, of an ultrasonic splicing device incorporating film trimming mechanism; and

FIG. 7 is a view taken along the line 7-7 in FIG. 6.

THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, there is shown an anvil or stage 11 of steel or other suitable metal having a transverse gap 13 and a longitudinal channel 15 in the top surface. The trailing end 17 of a strip or length of film and the leading end 19 of another strip or length of film (assuming film travels from left to right) are positioned on the anvil 11 with their ends substantially square, and flush with the sides of gap 13.

A short length of splicing tape 21, which has the same width as the film, is positioned across the gap 13 with its end portions resting on narrow areas extending across the entire widths of the'lengths l7 and 19. Tape 21 should include at least a surface portion which comprises a thermoplastic resin; but, if desired, the entire tape can be such a material. An ultrasonic horn 23 having a planar end surface is applied on the top of a tape or patch 21 so as to hold the ends of the patch firmly against the end surfaces of the film lengths. The planar surface may be smooth, or it may be provided with a matte finish, or other pattern such as serrations. Ultrasonic energy from a transducer (not shown) is then applied to horn 23 for a period long enough to cause the thermoplastic surface of the patch to melt at the interface and unite with the thermoplastic film base to effect the splice, e.g., a fraction of a second, such as 0.5 second, and the ultrasonic vibrations are then discontinued. Cooling of the splice and hardening of the softened plastic occur so rapidly that no waiting time is required after vibrations cease, and no auxiliary cooling air stream is needed.

Then the spliced film is removed. The operation. is repeated when the trailing end of film 19 is ready to be joined to the next successive length of film. Of course, when the joined films are traveling from right to left, it is the trailing end of film 17 that would be joined to the next length.

It is advantageous for the top surface of anvil 11 to be essentially horizontal immediately adjacent the edges of gap 13 at 11a and 11b (say for 3/32 inch), and to slope outwardly and downwardly in opposite directions away from the gap (say at 2 angles) at 11c and 11d to assure the strongest possible splice, without embrittlement. Splicing tape 21 overlies the areas 11a and 11b and extends for a short distance down the sloping areas 11c and 1 1d.

The splicing tape 21 can be constructed in several different ways for operability in our novel method. FIG. 3 shows splicing tape which comprises a top layer 27 of paper, such as kraft paper, laminated to a layer 29 of a synthetic resin, such as polyethylene terephthalate, which in turn carries an integral coating 31 of a thermoplastic adhesive material having a thermoplastic resin as an essential ingredient. Paper is advantageous because it provides a writing surface upon which to place identifying indicia for orderly processing of the film; because it increases friction and acts as a cushion to prevent slipping of the splicing patch under the pressure of the horn; and because it prevents melting of the patch itself. In the splicing patch or tape shown in FIG. 4, the top layer 33 is paper, such as kraft paper, bonded to a synthetic resin sheet 35, such as polyethylene terephthalate, which in turn is bonded to a sheet 37 of kraft paper carrying the thermoplastic adhesive layer 39.

FIG. shows on an enlarged scale and schematically the nature of the final splice which has been effected by our novel method. The two lengths l7 and 19 of film comprise thermoplastic film base 43 and 45 carrying on their bottom sides photographic emulsion layers 47 and 49, and on their top sides rem jet antihalation layers 51 and 53. The splicing tape 21 comprises kraft paper carrying a thin layer 55 of the thermoplastic adhesive, which is unchanged above the gap 13 between the ends of the film lengths, but which is intimately mixed together and united with the rem jet and with a surface portion of the film base 43, 45 on areas 57 and 59 near the ends of the splicing tape where it overlaps the film lengths.

Referring .to FIGS. 6 and 7, there is shown splicing apparatus similar to FIG. 1, but having two separately actuatable trimming knives 63 and 64, both independently pivoted at 65 on a bracket 67 projecting from anvil ll. Knives 63 and 64 are positioned above gap 13' and are swung downwardly one after the other by the operator to trim off projecting ends of film lengths, ending their strokes within the gap below the film lengths. The ultrasonic born 23 is moved downwardly to press the splicing tape against the film lengths and unite it thereto ultrasonically. Then the horn 23 is raised, the spliced lengths are removed, and the knives 63 and 64 are raised to their initial position in preparation for the next splice. This apparatus is particularly advantageous because it is not necessary for the operator to position the two lengths of film so that their ends are precisely flush with the sides of gap 13'.

The principles of the invention have been described by way of illustration as applied to the splicing of polyethylene terephthalate photographic film, but it is to be understood that splicing in the manner described can be performed successfully with other types of thermoplastic film base materials which are well known to the film art. Among these may be mentioned cellulose acetate, cellulose nitrate, polyethylene, polyvinyl chloride, copolymers of polyvinyl chloride and polyvinyl acetate, and polyvinylidene chloride. Successful results can be secured with films of these and other thermoplastic materials of any commercially available thickness, such as from 0.001 inch up to 0.015 inch. Also, the principles apply to films other than photographic, such as magnetic tape, when for some reason a direct film-to-film lap splice is unsuitable.

Any suitable commercially available dry, non-tacky adhesive coating 55 containing a thermoplastic resin ingredient can be employed, such as a commercially available adhesive comprising a butadiene-acrylonitrile copolymer (a nitrile rubber) mixed with a phenol-aldehyde resin. One such adhesive is sold by National Starch and Chemical Company as Resyn 36-6326. Other suitable thermoplastic adhesives are described in Canadian Pat. No. 564,192 and British Pat. No. 785,403. Other suitable adhesives are polyethylene and polyethylene terephthalate carried in thin layers on the atch. The adhesive IS applied to the patch in any conventiona way, as by coating on the patch a solution in an organic solvent which is then allowed to evaporate, leaving a dry, non-tacky coating.

The ultrasonic vibrations can be generated in any suitable way, as is well known to the ultrasonics art. Reference is made to the U.S. Pat. No. 3,022,814 of A. G. Bodine, Jr. which describes both magnetostrictive vibration generators and piezoelectric vibration generators which are suitable for the present invention. Generally, a vibration frequency between 20,000 and 40,000 cycles per second is used, but higher or lower values are operable.

It is preferred that the ultrasonic horn 23 be applied to the splicing tape 21 to effect the bonds, as it has been found that smooth continuous splices are obtained in this way. However, our novel method is operable when the relative positions of the film lengths l7 and 19 and the splicing tape 21 are inverted so that the horn 23 is applied to the film lengths.

By the rem jet antihalation layer on photographic film is meant the well-known translucent layer containing an opaque substance which is conventionally on the side of the film opposite the silver halide gelatin emulsion side. This rem jet layer may comprise a thin layer of plain gelatin containing an opaque substance, and may or may not contain an antihalation dye. Instead of gelatin there may be substituted such binders as casein, albumin, interpolyamides, agar-agar, polyvinyl alcohol, polyacyl amides, polyvinyl acetals, cellulose acetate propionate, and cellulose hexa or tetra hydrophthalate. Reference is made to US. Pat. Nos. 2,327,828; 2,271,234; 3,091,535; and 3,392,022 for more detail.

' The-invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim: I l. A method for connecting together two strips of thermoplastic films for transport through a photographic processing device in which at least one strip has a thermoplastic film base provided with a photosensitive emulsion layer on one side thereof and an antihalation layer on the other side thereof characterized by removability in a photographic processing solution, comprising the steps of:

positioning said strips with the leading and trailing ends thereof in longitudinal alignment substantially in one plane with the emulsion layer of one strip in contact with an anvil having a gap and with the leading and trailing ends extending across at least one side of the gap;

severing the leading and trailing ends of said strips along each of the sides of the gap to provide two spaced apart film ends;

placing a splicing tape comprising a paper having a thin coating of thermoplastic in overlapped relation to said spaced apart film ends with the thermoplastic coating in contact with the antihalation layer of said one strip; and applying ultrasonic energy simultaneously to said tape and said spaced apart film ends for uniting said tape to said film ends by causing the antihalation layer to melt and the thermoplastic coating of said tape to intimately mix and unite with the thermoplastic of said film base. 

